Arsmirandite is a rare volcanic mineral discovered in the fumaroles of the Tolbachik volcano in Russia. It typically appears as small, bright yellow to yellowish-orange platy crystals associated with other fumarolic minerals in high-temperature environments.

Hardness

2-3

Mohs

Luster

Adamantine

Streak

Yellow

Transparency

Translucent

mineralrare

Arsmirandite

Hardness: 2-3
Luster: Adamantine
Streak: Yellow
Transparency: Translucent

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Is this arsmirandite?

5-step field check

Run through these checks against the specimen in your hand. The more boxes tick, the more confident the ID.

1
Test the hardness
Try to scratch arsmirandite with a known reference. Arsmirandite sits at Mohs 2-3 — softer than the next harder reference, harder than the previous one.
2
Check the streak
Drag the specimen across an unglazed porcelain plate. Arsmirandite leaves a yellow streak.
3
Read the luster
Hold the specimen under a strong light. Arsmirandite typically shows a adamantine luster.
4
Match the color range
Compare against the expected color range: yellow, yellowish-orange.
5
Look at form & habit
Crystal system: triclinic. Typical habit: platy crystals.

Often confused with

Arsmirandite vs. its common look-alikes — and how to tell them apart in the field.

mineral

Lammerite

Mohs 3.5

How to tell apart: Streak differs — Arsmirandite leaves yellow, Lammerite leaves light green; luster reads adamantine on Arsmirandite and vitreous on Lammerite.

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Often found alongside arsmirandite

Minerals reported to co-occur with arsmirandite. Spotting these in float or country rock is a strong cue you are in the right ground.

All properties

Chemical formula: NaCu₄(AsO₄)₃
Mohs hardness: 2-3
Density: 5.32 g/cm³
Colors: Yellow Yellowish-orange
Streak: Yellow
Luster: Adamantine
Transparency: Translucent
Crystal system: Triclinic
Crystal habit: Platy Crystals
Cleavage: None
Rarity: Rare
Uses: Collector
Host rock: Fumarole Deposits
Typical price: $200-1000+ per specimen

Where rockhounds find arsmirandite

Classic worldwide localities

Tolbachik volcano, Kamchatka, Russia

Field-hunting tip

Look in fumarole deposits country — that is the host setting where arsmirandite typically forms. If you start seeing tenorite, hematite, sylvite in float, you are in the right ground. Field specimens usually show a platy crystals habit, so train your eye for that shape before scanning the outcrop.

Common questions

How do you identify arsmirandite?+

Mohs hardness is 2-3. It typically shows a adamantine luster. The streak is yellow. Common colors include yellow, yellowish-orange.

Where is arsmirandite found?+

Notable localities include Tolbachik volcano, Kamchatka, Russia.

How much is arsmirandite worth?+

Typical asking prices fall in the range of $200-1000+ per specimen. Quality, size, and provenance can move individual specimens well outside that range.

Is arsmirandite safe to handle?+

It contains toxic constituents. Contains arsenic and copper; wash hands after handling and avoid ingestion or inhalation of dust. Handle with care, avoid grinding or breathing dust, and store separately.

What rocks look like arsmirandite?+

Arsmirandite is most often confused with Lammerite. A quick hardness test and a streak check separate the look-alikes faster than color alone.

What minerals are found with arsmirandite?+

Arsmirandite commonly co-occurs with Tenorite, Hematite, Sylvite, Halite. Spotting any of these in float or country rock is a useful trip signal.

What kind of rock does arsmirandite form in?+

Arsmirandite typically forms in fumarole deposits. Working float back to the host body is the standard way to chase a fresh occurrence.

What is arsmirandite used for?+

Arsmirandite is used in collector.

Find arsmirandite on the map

RockHoundR shows mapped rockhounding spots, access rules, and lets you log every find.